The Computer Thing From Hell

[@TechTimeTraveller]

Sorry it took so long.. covid blew up 3 weeks in April. And brain fog is a real thing. But I did get it together and invested in a new Yeti X mic which I hope will put our audio problems to rest. Enjoy and thanks so much for watching!

[@MichaelXX2]

I highly recommend not using noise reduction with this new mic. A little hiss is a lot more tolerable than the warbling artifacts that NR introduces. Love the channel!

[@joshuamacdonald4913]

I'm glad you made it out the other end ok.

[@randomfrequency]

Sounds great

[@GrannyBender]

@Nny Yeah, this thing is nasty! My girlfriend caught it mid 2020, lost her sense of smell completely, it's still really slowly coming back; after 1.5 year of relationship she sent me a message saying something like "holy shit, I can finally detect and recognise your smell!!?"

[@GrannyBender]

No worries, take care!

[@mistwolf]

40 years ago some guy was having the same problems with his homebrew and gave up, unaware that someday someone would pick up his work without knowing it never worked. ;)

[@ArneLap]

This is exactly what i was thinking :)

[@ArifGhostwriter]

I find this kind of thought mind-boggling, almost! It's like when you're working on an old car & you have to pull something buried for the first time in the vehicle's life - I wonder about the human that put it there - who were they, what kind of a life did they have, etc!

[@tateg.7530]

"I hear EEPROM island is a nice place to visit, but just don't get too much sun" ...Sir, you are an electronics nerd of the highest magnitude, I tip my hat to you!

[@ForgottenMachines]

4:03 I concur!

[@MarkMcCluney]

Yeah, that took me a minute but I get it...

[@sirspamalot4014]

It wasn't until he completely faded away that I realised what the joke was, but it was still funny

[@the123king]

I had myself laughing at that one. My wife was looking at me funny

[@CreeperOnYourHouse]

*EPROM. EEPROM isn't light sensitive.

[@pevkh8359]

I love jour videos

[@pevkh8359]

The Borduper Conector Bort on The Right To me sins like an Internal Comunication Bord

[@Lantertronics]

Your level of stick-tuitive-ness is off the charts.

[@Hykje]

That thing was probably the reason for the estate sale.

[@youreyesarebleeding1368]

If that guy were still around, he would think this video is awesome.

[@pevkh8359]

The emty eprom is Clearly not important

[@gmosphere]

Looks like you time traveled back to 1977 and then went dumpster diving In steve Wozniak's garbage.

[@Jim202030]

Dude... love this project / vid / thing..

[@bitrage.]

Those hand made breadboards are beautiful...

[@TechTimeTraveller]

Really well organized I must say. Whoever built this thing knew what they were doing.

[@vwestlife]

Bongo Madness!

[@TechTimeTraveller]

Isn't it great?

[@malectric]

Back in the 70s, microprocessors were expensive and ones able to execute meaningful programs almost non-existent. Hard-wired logic and logic design was both science and an art form. Far from just using bits and pieces lying around in the junk box, the designer would have gone to a lot of trouble to design this with all its video timing (sync pulses etc.) and it would have cost him/her a good deal. The machine was originally known as a dumb terminal (a display/input device) communicating with a computer via a UART-fed RS-232 interface. EPROMS were used for a number of functions in those days; specifically ASCII-encoding of a keyboard matrix, character-generation, a simple way of deriving timing signals from a binary counter rather than using a plethora of decoding logic and so-on. Erasable devices make bug-fixing, design modification and feature-adding easy. While the mains wiring is quite unsafe, I guess the builder never intended the unit to be used by others. It should never have been sold in that condition. I built such a terminal back in the early 1980's using a 6809 micro for doing all the smarts, a 6845 programmable video controller for generating the video timing signals, character memory addressing and so-on. Mine is in my study, is clean and tidy has all the smarts and video logic on a single PC board, the keyboard encoder on another and still works (uses the same keyboard as this one incidentally). The operating system for my terminal runs to 40 or so pages of commented 6809 code. I designed my own EPROM keyboard encoder and character generator and included a static RAM for programmable characters. Please do not be too disparaging of the efforts of early builders and hobbyists. I could say an awful lot in a similar tone about the disposable garbage that is built and sold these days with the sole object of making money. And these days I answer questions on another forum in the vein of, "how do I build a logic circuit to give a 0 output if A and B and ~C =1?", never mind the intelligence required to design something like "the Computer Thing From Hell". BTW the two main sources of problems you will run into with hardware built like this is poor IC pin to socket contacts caused by poor tinning on the IC pins, corrosion in the sockets, de-springing of the socket contacts themselves and above all, bead tantalum capacitors. I would replace all of the latter - they can short-circuit for no good reason at any time. They were often used for voltage regulator bypassing due to their low-ESR characteristics but modern miniature electrolytics with short leads will do the job just as well. And shorted power supplies in a system containing multiple-supply chips (like the old 2101s and other NMOS devices) can also cause chip failure. Taking time to scrape corrosion off the IC pins and applying good contact treatment to the sockets (or removing the sockets and soldering the chips in directly better still) can save a lot of trouble-shooting time in the long run. One last little thing: the wavy picture suggests that the picture tube yoke is being influenced by stray magnetic fields from a nearby mains-frequency power transformer.

[@AmauryJacquot]

BNC for video is not "old style", it is currently used in all pro video equipment.

[@winstonsmith478]

There's a TV series called Graveyard Cars where they restore classic cars found in horrible condition. Maybe you should call these episodes Graveyard Hardwares?

[@AiOinc1]

Guy here on KZbin called shango066 does a series of videos called resurrections, not restorations as he's not changing every part, but changing just enough to bring it back to life. Could also call it a ressurection. If you like that type of content might wanna check him out too

[@brandonupchurch7628]

My dad calls my old PC collection "the computer graveyard"

[@askhowiknow5527]

“Graveyard Hardware” would actually makes sense in our dialect of English :*

[@AiOinc1]

@@askhowiknow5527 graveyhardware

[@daveash9572]

Except just like it's one lego brick and two lego bricks (there's no such thing as 'legos' except something that belongs to lego), the plural of hardware is hardware

[@garbleduser]

When RAM dies, it goes to the Delay Line in the sky...

[@joshuagessner1422]

this is really cool didnt really know about homebrew computers and terminals

[@Journey_to_who_knows]

This looks like it would control some scrap metal time machine in a apocalypse movie

[@pogostix6097]

This thing reminds me of some weird kitchen gadget nobody knows the name of anymore. Clearly it had some purpose, it was made for a reason, but nobody knows what it is, and the more you try to guess, the more you are confused.

[@herzogsbuick]

That introduction is so good, I had to stop the video when it was over to come down here to tell you that.

[@TechTimeTraveller]

Many thanks! I like to experiment a bit with different styles of intro.

[@baremetaltechtv]

I've watched this video several times, still amazes me how you bring these old machines back to life. It is a real shame the seller separated the terminal and the computer, this guy obviously had his own way of doing things and having both would have been quite a treat :) I hope someday the guy who bought it sees your video and leaves some contact info so we can bring the two machines together again.

[@TechTimeTraveller]

Unfortunately separation seems to be common. I try to assume it's just because these sellers buy things in a group and not because they're just trying to wring as much $ as possible from the deal. Some unfortunately do that with systems that have valuable keyboards unfortunately.

[@SKCro.]

16:34: the top of the screen be vibin'

[@KennethSorling]

It was unsatisfying not to get a successful conclusion to this. Still, I'm impressed by your technichal savvy, your sleuthing skills, your near-angelic patience, and, frankly, your courage. I hope you crack this nut.

[@belstar1128]

I love this archaic homebrew hardware.

[@joefish6091]

It was quite expensive back in the day, the Byte and PCW magazine archives are online, the 70s prices for computers and components are intriguing.

[@belstar1128]

@@joefish6091 Yea it was cutting edge back then this may look cheap but that is because the builder had to compromise it was the only way to afford it a nice pre build system would have been unaffordable.

[@techguy9023]

I immediately thought “Don Lancaster-TV typewriter”. My misspent youth following Steve Circia’s Circuit Cellar in Byte mag happily wire wrapping a Zilog sbc then a 8051 sbc.

[@edgeeffect]

That introduction was absolutely amazing... and so very true.... I have a terrible problem with "other people's garbage"

[@MadameSomnambule]

Same. It's why I love thrifting and finding old shit on ebay and etsy. Though most "other people's garbage" I tend to buy are vintage clothes, audio tapes, and records and maybe the odd computer thing or two. lol

[@ivorj4715]

The connector was named the BNC (for Bayonet Neill-Concelman) after its bayonet mount locking mechanism and its inventors, Paul Neill and Carl Concelman. Neill worked at Bell Labs and also invented the N connector; Concelman worked at Amphenol and also invented the C connector. (Source Wikipedia)

[@TechTimeTraveller]

Thank you! Was BNC applied just to those smaller locking types? On some of my monitors I have a port that resembles a super sized RCA phono style plug with threads around the rim.. the connector that mates to it has a really big pin and screws onto it. I've read people referring to it as BNC but I don't think so. It's much larger.

[@ivorj4715]

@@TechTimeTraveller That may be an F type connector

[@scottlarson1548]

Most of that is stuff straight from a 1970s Radio Shack. They had those Archer breadboards with edge connectors as well as IC sockets with wire wrap posts. It's amazing that back then anyone could walk into a Radio Shack then go home and build something like this.

[@TechTimeTraveller]

I would give anything to be able to do that sort of thing. I was too young when Radio Shacks really were Radio Shacks.. most of my life they've been basically retail toy/stereo/computer dealers.. and then later The Source (Canada).. which at most would sell you solder and some wire.

[@scottlarson1548]

@@TechTimeTraveller They still had some hobby stuff as late as the 1990s. In 1991 I was working on a client's computer in the middle of nowhere Minnesota and saw that one board had been configured wrong when it we shipped it to the client. Two pins needed a shorting block which I didn't have because I'm a software person. I was tempted to use a paperclip or something, but I saw there was a Radio Shack across the street. I went in and that place *still* had a wire wrap tool and wire wrap! So I was able to do a professional job shorting the two pins.

[@asteroidrules]

It's annoying how hard it is to find electronic components in person nowadays, yeah online stores mean the amount of components anyone can get has gone up considerably, but the inability to actually check the physical thing before buying it, and having to wait multiple days and pay extra fees for shipping, has made the hobby harder in some ways.

[@TechTimeTraveller]

@@asteroidrules I really struggle with buying parts like the card slot etc.. as you said it's really nice to be able to see the physical thing.

[@scottlarson1548]

@@asteroidrules Also it sucks when you just need a capacitor or resistor and the shipping is $5 then you have to wait for a week. Back then you could go to any Radio Shack in the country and get these components for a few cents. One day at school I decided to build a headphone amplifier, so after school I went to Radio Shack and got *all* of the components including a 741 op amp and had the thing completed that evening.

[@studiokadaver]

This video alone deserved a follow.

[@TechTimeTraveller]

Thank you!

[@caturdaynite7217]

I saw that power supply and I was like.. NOPE!

[@elektron2kim666]

Basically a modem terminal or a teletypewriter.

[@paullee107]

Yer videos are so great - we need to get yer subs way up!! I’m in; I can see how much time goes in, I’d love yer help!! Great job, thanks for sharing.

[@TechTimeTraveller]

Many thanks!

[@wizardofeyes]

I see a number of PolyPaks renumbered ICs. The big silver characters are the giveaway. Those were good days.

[@Oddzball3]

Love your videos

[@TechTimeTraveller]

Thank you very much!

[@ellindsey000]

The first EEPROM, whose contents are shown at 22:20, looks like it's being used to decode specific control characters. They're using the EEPROM to replace a pile of decoding logic, by feeding the character code into the address pins and then having the eight data pins out of the EEPROM each indicate a specific character match. Notice how all the codes are 0x00 except for 8 characters (0x07, 0x09, 0x0B, 0x0C, 0x10, 0x16, 0x1A, 0x1C) each of which will set exactly one output line from the EEPROM high. This would have been used to generate control lines that trigger events such as backspace and newline to happen when those keys were pressed. I'm not sure what specific characters they're decoding, this looks like it might not be using the standard ASCII mapping. The second EEPROM, contents shown at 22:22, looks like it's performing some kind of character remapping. In a similar way to the previous EEPROM, the character code from the keyboard would be fed into the address lines, and the data out would then contain the remapped character code. It looks like most of the characters are passed through unchanged, as the data contents of the EEPROM are equal to the address for most of the address inputs, but characters in the range 00-0F and 7E-7F have been remapped. I'm not completely sure why they needed this, maybe the character generator chip doesn't have the same character mapping as the keyboard and they needed to change some things around. The third EEPROM, contents shown at 22:32, looks like it's also being used to generate specific control signals based on the character inputs. Most of the values in this EEPROM are 0x80, and I suspect that was being used to generate the signal to move the cursor one space to the right after a normal character was typed. It's also generating some other codes for some of the remapped and control characters, though again I'm not sure what as I don't know what the mapping is. Perhaps this one is being used to generate cursor movement in general? I'd have to see the schematic to say for sure.

[@ellindsey000]

On further examination, the first EPROM seems to be decoding bell, horizontal tab, vertical tab, form feed, DLE, idle, and either start of text and end of text, or substitute and file character control codes. The second one is remapping many of the ASCII control characters while leaving the actual printable characters unchanged. I'm not sure why, maybe this thing originally used a non-ASCII keyboard and then when they changed it to use an ASCII one the builder decided it was easier to remap the control characters rather than rework the logic elsewhere. The third EPROM looks like it's decoding line feed, escape, and maybe backspace and carriage return. And the EPROM whose contents are shown at 22:47 is just baffling. That doesn't look like a lookup table. Might be some kind of state engine, I'd have to see what the surrounding circuitry looks like to know for sure.

[@markussteinbacher8807]

@@ellindsey000 What an adventure to have computers in 1975.. Eproms (250ns) whre to slow back then for video state machine. you need a fast 82s100 or similar to do this. the screen wobeling could be a issue with grounding and of course powersupply caps. you get the 60hz inside the video generator (output amp?) I see at the end that the television is wipe on side if you have much screen content - please check video level on outout - seems the output amp is overdriven (!) - shouldn´t be more than 1V (!) on the output Vpp at 75 Ohms as I remember.

[@bobbjorkner7140]

in one shot, the proto card appeared severely warped.

[@TechTimeTraveller]

Yeah I think whatever substrate it's made of probably didn't take the moisture of the shed it was stored in too well.

[@bobbjorkner7140]

@@TechTimeTraveller I believe that the curvature made it so that when you place the weight on it the pins in the center at the most bowed out part would make contact while pushing away the pins on the other side inside of the socket, causing at least part of the issues. Thanks for replying,great video!

[@andueskitzoidneversolo2823]

as a person with schizophrenia, this is the best intro ever.

[@vasenkasi4846]

Based on the close-up of your hair, you're slowly turning from the Black Spy into the White Spy.

[@paulwratt]

essentially the benifits of homebrew from tyhe 70's. Even stored in the garbage pile it probably still ran up until you got it

[@ryanclelland6743]

It really is a shame that it was an estate sale you got it from. It would be so interesting to pick the brain of who ever made this.

[@TechTimeTraveller]

Yeah I so rarely get to do that. It sucks that we are losing all these first generation home computer guys to age. The rare times I'm able to talk to the original owner I get troves of interesting insights.

[@foxdavion6865]

@@TechTimeTraveller Most of the people still alive from that time period who were involved with computers are in their late 70s and are retired teachers/uni professors who worked with Minicomputers such as the PDP and IBM System/ series as opposed to first generation home micro. Unfortunately it's very rare to find anyone still alive who were early home micro hobbyists, especially ones with enough knowledge and money to build something like this home brew lower case as well as upper case ASCII terminal. Considering it was found in a shed, it's very likely the person who passed away was likely an inheritor of the device themselves.

[@khatharrmalkavian3306]

"Where RAM goes when it dies..." The bit bucket?

[@mheermance]

With regard to EPROM uses. Ben Eater has a video where he replaces a ton of discreet logic ICs with a single EEPROM, and made a comment that any collection of logic ICs can be replaced by one. After that programmable logic made a lot more sense to me.

[@TechTimeTraveller]

Yeah I guess as a relative novice my issue is I'm used to EPROMs as a data storage device for things like system monitor, BASIC etc.. I haven't really wrapped my head around how the data burned into one is used is the absence of a processor. I should have known it could be... many machines I have use an EPROM for keyboard encoding. I'm gonna have to watch those videos now.

[@snooks5607]

@@TechTimeTraveller imo it's probably all that talk about inputs being "addresses" that make people think of EPROMs only as data storage devices but yea physically they're just a big collection of programmable transistors (act of programming jams the gate into a desired position)

[@sebastian19745]

@@TechTimeTraveller Just think to a circuit that have only logic gates as a box with some inputs and some outputs. Take the inputs as the addresses lines of the EPROM and the outputs as the data lines. Now calculate for each combination possible of inputs the outputs result and write that data at the respective address. When replace the circuit with the EPROM, yo have the same functionality but less ICs so a simplest way to implement a schematic. Unfortunately, that approach was made many times and were used masked PROMS instead EPROMS to replace a CLC. When the PROM died, it is impossible to figure what circuit it replaced. I had an old computer that I want to rebuild but although I have the schematic, there is a bipolar PROM that nobody took the time to read, so that part of the circuit is impossible to build; also there are few computers in existence afaik.

[@v12alpine]

Similar to the PLA in a C64.

[@techguy9023]

I remember learning about Pal/gal logic in school. Write the equation and enter the code. Hit program. Your address decoder that took 17 74HCT chips is replaced with one.

[@pandakekok7319]

0:55 "But it's cheap!" "Yeah tell that to your divorce lawyer pal" LMAOOOOO

[@Alf_Pacino]

This was fascinating

[@askhowiknow5527]

That thing is definitely computer It’s the computerist thing I’ve ever seen

[@Denosophem]

Wow that think is an absolute monster! 5TB of storage space?

[@guiltygearalonecompl]

The Battletech nerd in me shivers when I hear the words “AC-30.” Just imagine…

[@icannotbeseen]

I love this intro

[@johnjoyce]

That rust was likely caused or promoted by pins and sockets with different metal compositions

[@blackterminal]

Someone spent a lot of time on that device

[@gregebert5544]

Oh, memories. I built a video terminal using the same Radio Shack ASCII keyboard encoder back in 1979 so I could get online nights/weekends when the timeshare system had no other users. Amazing dialup MODEM ran at 300 baud, much faster than the Teletype we had at school that was 110. The rest of my setup were kits from Electronic Systems : a TV typewriter that was 16 lines x 64 characters, Power supply, UART board, RF modulator so you could run the video into a TV set, and a MODEM.

[@TechTimeTraveller]

I have been looking for one of those Electronics Systems TVT boards forever. They just don't come up for sale. Probably because they look like random electronic junk.

[@gregebert5544]

@@TechTimeTraveller Sad to admit that I threw the entire board set into the garbage about 30 years ago when I got a VT100 and a VT220 from a past employer, because those were considered to be junk. The only value of the TVT board set is nostalgic, and most TVs could not display 64 characters very well because of their limited video bandwidth. I got nice results with a color TV by turning off the blue and red guns; the remaining green had no convergence issues. Blue-only and red-only worked OK, though not as visible as green. I had a smaller black-and-white TV, and it was actually harder to read than color (green). I did keep the Electronic Systems power supply for a few more years. A year later I moved-up to a real 24x80 display (SD System VDB-8024), and that absolutely required a real video monitor, so the TVT got boxed-up and ignored. The MODEM worked surprisingly well; very few bit errors even at 300 baud on standard telco, and of course that was with acoustic coupling (speaker and mic). Direct-connect was not legal. I miss those days of real homebrewing. Hard to believe when you had 64Kbytes of memory, and a pair of 8-inch Shugart floppy drives you had a top-tier machine.

[@MJRSoap]

Great now I'm curious and want to see a follow up

[@oliverherss]

Love the video! But I wish that you would have had a low-pass filter on the clips with a crt, as it greatly hurts my ears :)

[@TechTimeTraveller]

Sorry! I've learned to do that since. Sadly that was exactly what I was doing with this video.. but because the CRT didn't actually appear in the clips I didn't realize it was on and squealing. I got everywhere else except that one segment.

[@OscarSommerbo]

I am guessing that the "audio card" is the tape interface card.

[@TechTimeTraveller]

Yup.. its basically the equivalent of SWTPC's AC30 tape encoder. Doesn't work unfortunately but probably could with some tuning.

[@flatfingertuning727]

@@TechTimeTraveller How often did systems use hardware for audio encoding/decoding, and how often was that left to software? The only time I would think hardware would offer a big advantage would be if it would allow a system to boot off tape without needing a custom ROM, but from what I can tell hardware decoding was pretty common.

[@herbertpocket8855]

Oh man that spy v spy gag made me chuckle

[@Bata.andrei]

The garbage on the screen looks like some kind of alien alphabet. I think it would make a great movie prop for some kind of alien/post apocalyptic sci-fi movie :)

[@michaelwright2986]

Maybe this thing is a device for decoding the Voynich Manuscript?

[@Bata.andrei]

@@michaelwright2986 or maybe it's the very thing John Titor (if you don't know who he is, look it up, but beware of the rabbit hole :)) was looking for :)

[@michaelwright2986]

@@Bata.andrei Somehow, I missed him the first time round. And now the Time Cube only exists on the Wayback Machine, which is kind of too meta for words. I must read again Thief of Time, by Terry Pratchett.

[@justinc8157]

I love this thing.

[@williamharris8367]

My (non-expert) opinion is that this thing was either modified to over a long period of time to add more features, etc., or, possibly, it was a collaborative effort among several people. This would explain the multiple different circuit boards and overall bodged-together style.

[@TechTimeTraveller]

Could be. The estate saler seemed pretty convinced he was a lone inventor kinda guy.. so probably over time. Maybe the whole thing was set up differently in the beginning.

[@williamharris8367]

Do the date codes on the chips support this theory? Are some parts obviously older than others? (I do realise that a hard-core hobbyist would have an inventory of parts on hand, but we can only analyze the existing evidence.)

[@8bitwiz_]

Most of the chips look to me to be Radio Shack parts from the era. (The rest would be mail-order.) A lot of the chips Radio Shack sold were probably surplus, so in the late '70s you would find a bunch with 71-74 dates, sometimes earlier, and quite a variety of package and labeling styles. And there's a good chance that the basic design came from some magazine from the late '70s.

[@albertoftasmania]

That's fucking awesome. I want to make one.

[@AppliedCryogenics]

Great episode as always, but must state my opinion that perfboards aren't breadboards!

[@TechTimeTraveller]

Yeah.. the ones on the left are perf and the ones on the right.. depends who you ask. That machine was a bit of a jumble.. I was bound to mix things up.

[@AppliedCryogenics]

No mixup, good sir. I think I just dated myself by using 1979 Radio Shack terminology, and come to think of it, they called them "solderless breadboards", which implies the solderable version which I was neglecting. Pardon the ill-informed nitpick! Geek on, and feel better soon.

[@comlitbeta7532]

I have no idea of what i am watching, but i like the general vibes.

[@anonymousman3623]

Your comment on someone else’s garbage hit to close to home

[@bouldersoundguy]

BNC = bayonet Neill Concelman. TNC = threaded Neill Concelman.

[@lkscb6917]

apparently a lot of people skipped specifically to when the terminal's font was defined then that must be one popular font then

[@rotteegher39]

16:34 random "monk" in the middle of random computer nonsense: 🗿

[@paulb4uk]

Great work something like this must be a bit of a nightmare to diagnose .

[@TechTimeTraveller]

"No schematic? No problem!" 😀

[@wolfetteplays8894]

That radio shack joke aged me several years when I realized they’ve been closed since before I graduated high school

[@brianoconnell6459]

Smells to me like a Heathkit DIY terminal.

[@aetheralmeowstic2392]

I can hear the CRT whine in the background during one of your explanations.

[@TechTimeTraveller]

Yeah.. it slipped the net. I believe it's a segment where the CRT wasn't visible.. and I didn't realize it was on.

[@DaveF.]

gorgeous keyboard - reminds me of a BBC micro keyboard. Looks fantastic.

[@abaranihei2608]

Stop apologizing for the Videoquality its perfectly fine geeez 😂

[@TechTimeTraveller]

Well, the bits I was concerned about were the old shots from 2019.. lighting wasn't great. :) I've gotten picky about that as I've gotten more experience.

[@abaranihei2608]

@@TechTimeTraveller i know i didnt wanted to be rude sorry 🙂

[@TechTimeTraveller]

@@abaranihei2608 oh you weren't rude at all! No need to apologize!

[@parkerlreed]

I am very happy you showed up in my recommendations. Wonderful video and presentation!

[@douro20]

Looks like some of those logic chips have milspec numbering on them.

[@MichaelKingsfordGray]

Those green edge-connectors were the bane of HP repair technicians in the 1970s and 80s. The plastic expanded, causing the middle connectors to lose contact!

[@bass0129]

I'm watching this on a computer that I built thinking to myself "some dude in the future is going to buy my computer at an estate sale and pick it apart like this, wondering what I did"

[@mheermance]

Back in the day I had that Radio Shack keyboard PCB. I was going to build a Cosmac Elf and try interfacing that keyboard to it. But the skills of teenager me weren't up to the challenge. It didn't help that in a few years I was able to buy an Atari 800 xl for less than the cost to finish it.

[@TechTimeTraveller]

I never understood how you'd use an ELF with a keyboard. Were you planning to have it do video output also?

[@mheermance]

@@TechTimeTraveller The Popular Electronics articles described how to interface a parallel device to the Elf's data bus. So a machine instruction could read from the keyboard using an input instruction. For output I was thinking of using the 1861 pixie graphics chip. To glue this all together would require a ROM monitor reading, bitmap generation, and display. My ideas were sound, but I lacked the skills to pull them off.

[@freednighthawk]

I think, with the way the TV was acting, I'd drop a new crystal on there. That thing looked a bit sketch.

[@mikedrop4421]

Haha that into was genius. You find your suit?

[@TechTimeTraveller]

Yup. This hole I'm buried in is cold..

[@8088argentina]

OMG!! WASH IT!!! IT HAS SO MUCH LAND THAT YOU CAN PLANT SEEDS. SOMETHING SO COLLECTIBLE

[@hannescampidell]

when will there be part 2

[@CharlesRWard]

Remembering from the old days, an eprom will hold its program for about 30 years, may give you some trouble.

[@SisterRose]

That floaty wavey effect around 13 minutes in is so cool. can see an analog horror series using it

[@numberslettersstuff]

Its a shame that the estate sale didnt keep the computer and the terminal together. That bothered me.

[@TechTimeTraveller]

Yeah thats why I kinda rag on estate salers a little bit sometimes. They often don't take the time to research what they have (they can't.. they need to get stuff sold asap).. or they break up pieces to maximize $. The ones that break up mechanical keyboards and their machines because the keyboard is worth more by itself really irk me.

[@muxahx3096]

Strong respect. Dude you are not only one who had cognitive struggles after COVID .

[@TechTimeTraveller]

I didn't believe in the whole covid brain fog thing but.. I can't explain its occurrence any other way atm.

[@Arcaxon]

Absolutely love the content but sadly couldn't get past the 12:46 because of the horrible high pitch noise in the old footage; I am so glad you don't have that in your newer stuff. But keep it up; I normally don't comment but I felt bad I couldn't finish the video. ;w;

[@TechTimeTraveller]

Yeah sorry I am still mastering the whine detection and elimination. I cannot hear it and apparently it evaded my 'beta testers'. The footage in question didn't actually have the monitor in view so I wrongly assumed it was off and never looked at it. It's about a 1 min segment and then is gone afterwards as the rest has narration over it. Many thanks for trying. Always a bit of a learning process with this stuff!

[@Arcaxon]

@@TechTimeTraveller hey no worries; besides the video was so interesting I just skipped that part once I realized you were mostly showing the footage and the whine was gone other than that section.. Your videos are always super entertaining and hey if you need help with whine detection feel free to ask me but so far this was the only time ever it happened so don't worry! Haha you are doing great! Making vids is hard I know that from experience. Just keep it up dude it's fantastic!

[@johnjoyce]

Pretty sure the teeth on that connector wanted to be spade connectors

[@Phantom0fTheRouter]

EEPROM Island! Do you know what you did there? I do. Really nice callback to the Programmers Paradise Catalog.

[@davidprock904]

13:24 , the math formula to the meaning of life...

[@mohinderkaur6671]

Check Ground returns and VCC rails.

[@crabby7668]

Just a suggestion if you haven't spotted it already. Could the. ROM marked TVT function stand for TV Typewriter, as it was from around that period? Perhaps it was a decoder for that function. Just a guess.

[@TechTimeTraveller]

I think so. I think this machine is definitely a TVT of sorts. In my ignorance I did not realize something with no CPU could read and use EPROM data. I now think the EPROMs contain things like terminal functions, translation tables etc.

[@crabby7668]

@@TechTimeTraveller well best of luck working it all out. I look forward to seeing the video when you have sorted it.

[@owlstead]

Cheap? Those switches & caps should be worth their weight in gold by now!

[@trabant601e]

If I was a computer, that would be me

[@herbertpocket8855]

Woah, what a whacky device

[@andypeterson2126]

Well, technically, that’s the first iPhone!

[@techtheguy5180]

Eprom Island is the place to be at, man, once your wife kicks you out of the home. Why don't they understand that what they call junk is our hobby?

[@fanglordoftime]

Nice work I would like more info on those dip connectors in red

[@X-OR_]

Is there a on power reset circuit that restarts all the Clocks and Ram ?

[@J.C...]

Lmao @ "...these British/US things." 🤣🤣🤣🤣

[@hessex1899]

The garage is a perfectly reasonable place to go on fire. If you want to minimize the probability of going on fire you should go to a SeaParks.